In the present work, the rheological and mechanical properties of polypropylene /thermoplastic starch (PP/TPS) and acrylonitril-butadienestyrene/ thermoplastic starch (ABS/TPS) blends were investigated. Starch was plasticized using glycerol, and blends were prepared using a laboratory scale with single screw extruder. Rheological properties of the prepared blends were determined using a capillary rheometer. Mechanical properties were studied in term of tensile tests, stress at break, strain at break and Young's modulus were determined.